Ring laser angular rate sensors, also called laser gyros, are well known in the art. One example of a ring laser angular rate sensor is U.S. Pat. No. 4,751,718 issued to Hanse, et al., which is incorporated herein by reference thereto. Present day ring laser angular rate sensors include a thermally and mechanically stable laser block having a plurality of formed cavities for enclosing a gap. Mirrors are placed at the extremities of the cavities for reflecting laser beams and providing an optical closed-loop path.
Associated with such sensors is an undesirable phenomenon called lock-in which has been recognized for some time in the prior art. In the prior art, the lock-in phenomenon has been addressed by rotationally oscillating or dithering such sensors. The rotational oscillation is typically provided by a dither motor.
Dither motors of the prior art usually have a suspension system which includes, for example, an outer rim, a central hub member and a plurality of three dither motor reeds which project radially from the hub member and are connected between the hub member and the rim. Conventionally, a set of piezoelectric elements which serve as an actuator is connected to the suspension system. When actuated through the application of an electrical signal to the piezoelectric elements, the suspension system operates as a dither motor which causes the block of the sensor to oscillate angularly at the natural mechanical resonant frequency of the suspension system. This dither motion is superimposed upon the inertial rotation of the sensor in inertial space. Such dither motors may be used in connection with a single laser gyro, or to dither multiple laser gyros. The prior art includes various approaches to recover inertial rotation data free from dither effects.